


All I Need Is Uranium

by Aeon_Wolf



Category: Supergirl (TV 2015)
Genre: 1/3 fluff, 2/3 Sin, F/F, Fluff and Smut, I just wanted an excuse to write sin, Oneshot, have fun
Language: English
Status: Completed
Published: 2017-02-23
Updated: 2017-02-23
Packaged: 2018-09-26 10:54:33
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,696
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/9892211
Author URL: https://archiveofourown.org/users/Aeon_Wolf/pseuds/Aeon_Wolf
Summary: Imagine person A as being a science major of some sort. Person B, being playful, tells person A “I have the Fluorine, Carbon, and Potassium. All I need is Uranium.”OrOne of Lena Luthor's biggest turn ons is her girlfriend, Kara Danvers, babbling about science. Fluff and smut ensue.





	

**Author's Note:**

> Imagine person A as being a science major of some sort. Person B, being playful, tells person A: 
> 
> “I have the Fluorine, Carbon, and Potassium. All I need is Uranium.”

Lena rest her head on her hand while her elbow was resting on the top of the couch in Kara’s apartment. Lena knew she had a lazy smile plastered on her face while she listened to Kara talk. She just couldn’t help it, she loved it when her girlfriend talked science. It was kind of sexy to Lena. 

As a science prodigy herself, Lena rarely found anyone to have an intellectual conversation with. Her IQ was far above the average person. It was even above her brother’s number. Lillian had been furious at that. That the “halfling” Luthor was smarter than her darling boy and took every opportunity when Lena was young to belittle her intelligence. She was never outright abusive about it, but she was more subtle about it. Lillian would instead force Lena into becoming a socialite, rather than hone her intelligence. But Lillian could never truly squash Lena’s brain. 

The youngest Luthor got her opportunity to explore and grow in college. She took all sorts of upper division science and engineering classes, even venturing into graduate classes as an undergrad. She found that was where she truly loved being. 

But she was never able to really bond with anyone in the department because her mind was so far ahead of anyone else. Sure, she had friendships within her department, but she never found a real connection with anyone. Until Kara came along. 

At first, she was sure that Kara wouldn’t be able to understand the more scientific parts of her mind, though she still was smitten with Kara at first sight anyway. But a few weeks after they had started dating, Lena had gone to visit Kara after a particularly disappointing day. She had been so close to a breakthrough on one of L-Corp’s prototypes. Kara had asked her what was wrong and Lena had just brushed it off, insisting Kara wouldn’t understand. But Kara had pushed and Lena had reluctantly explained. 

To her surprise, Kara followed her train of thought to the letter and had even contributed an idea that Lena, nor any of the others in R&D had thought of. Lena had initially been shocked. She didn’t doubt Kara’s intelligence, but she had no idea that it was up to par with her own. And after Kara had told her about her planet of origin, she realized that Kara was smarter than she had ever given her credit for. And way more likely, was even more knowledgeable about science than Lena was herself. 

And so the couple would relish in just sitting on the couch in the evening, talking. Lena would listen to Kara ramble on about scientific breakthroughs they had made on Krypton. Every once in awhile, Lena would ask for clarification or explanation of things that she had never heard of and Kara would excitedly tell her. It made Lena’s heart warm at how happy Kara was to have someone that she could really have a conversation with. And could follow her. There were a lot of very smart people in Kara’s life; her sister Alex, best friend Winn, Mon-El to some degree since they had come from sister planets though he wasn’t as knowledgeable as other Daxamites had probably been, and the list went on. But none of them could really follow Kara, especially since the blonde had been poised to join the Science Guild before Krypton died. She had told Lena that she was one of the most promising minds that would have joined the Guild in years. 

So Lena took every opportunity to indulge her girlfriend in stimulating conversation. Because she knew Kara craved it. And that was one thing that Lena could provide to the girl that had almost everything, yet needed so much. 

“Lena, are you even listening to me?” Kara inquired. Lena blinked. 

“What? Sorry, Kara, my mind was elsewhere, repeat that?” Lena said sheepishly. Kara just laughed before taking Lena’s free hand and pulling her girlfriend closer to capture her lips. The couple shared a short kiss before they separated.

“I was just asking you about how that new carbon fiber fabric development was going,”  Kara stated. 

“Oh. It’s coming along. It’s still in the early stages, though. I’m hoping we can start testing in the next few months, though.” Lena said absentmindedly. L-Corp had recently been trying to develop a low-cost, more flexible bulletproof fabric. She was hoping to be able to create more flexible and less bulky bulletproof clothing. Admittedly, she may have had Alex and Maggie in mind when she had pitched it to the board. The couple had grown on Lena over the last few months. 

Kara nodded. “Are you okay babe? You seem a bit out of it today.” Kara asked, a bit of concern lacing her voice. 

“No, I’m okay,” Lena said with a smile. “Listening to you talk science always brightens my day.” Kara beamed. 

“I’m glad! Because being able to talk with you about it is the best. You actually understand me and most of the concepts I’m talking about.” Kara babbled before starting off on a discussion on particle physics. Lena just sat back and listened to Kara talk, nodding and mumbling her understanding once in awhile. 

Lena’s eyes remained fixed on Kara’s beautiful face. She had to admit, listening to Kara talk this passionately about something, especially their shared interest was kind of a turn on. And Lena found herself getting a little warm. Lena, without realizing it had raised an eyebrow listening to Kara and the blonde was now looking at her intently. 

“What, do I have something on my face?” Lena asked. Kara shook her head. 

“No, it’s just…. You were doing that eyebrow thing again. And that’s always a sign… of.. Well…” Kara blushed. Lena chuckled. 

“I admit Kara, listening to you talk physics is always a turn on.” Lena purred, scooting closer to Kara on the couch. Kara also drifted closer to her girlfriend. 

“Really?” Kara asked cheekily. Lena knew that Kara was a little minx when she wanted to be. Underneath the cute outfits, pastel colors and innocent demeanor was a little sapphic goddess that liked to come to out play when they were alone. “If I tried to use science to turn you on, would it work?” Kara asked. Lena shrugged. 

“So, if I told you I have the Fluorine, Carbon, and Potassium. All I need is Uranium, what would you do?” Kara whispered into Lena’s ear before abruptly lifting Lena off the couch and into her lap. The CEO yelped at the suddenness of her girlfriend’s actions before placing her hands on the back of the couch, on either side of Kara’s head. Her eyes had darkened at the words that had come out of Kara’s mouth. 

To any normal person, they wouldn’t have meant a thing. But Lena understood. It was a cheesy and honestly bad pickup line, but Lena couldn’t help her reactions to it. Kara had basically just said ‘I have the F, C, and K, all I need is U.’ Lena groaned, burying her face into Kara’s neck, breathing in her girlfriend’s scent. She gently pressed her lips against Kara’s neck. 

“I would first tell you that that was awful. And then I would rip your clothes off and fuck you on this couch.” Lena mumbled between kisses. Kara whimpered, placing her hands on Lena’s hips. 

“Do it then.” Kara challenged. Lena just raised an eyebrow, pulling back from Kara’s neck. 

“You’re not going to be able to walk to the bedroom later when I’m finished with you.” Lena accepted before pulling Kara in by the collar of her shirt, smashing their lips together. Lena sucked Kara’s lower lip into her own mouth, biting down gently. Kara’s hands began to wander her girlfriend’s body, eventually grabbing Lena’s ass, pulling her girlfriend’s body closer to her. Lena pressed her hips into Kara’s abs, taking one of her hands off the couch, cupping Kara’s cheek. 

Lena’s hip gyrated slightly against Kara’s body, causing the blonde’s breath to hitch slightly. Her hands left Lena’s ass, flying towards Lena’s own shirt and ripping it from her girlfriend’s body. Lena chuckled into their kiss, before breaking it for a minute. “I should be mad because I really liked that shirt, but fuck, that was hot.” Lena murmured. 

This time, Kara pulling Lena’s face back to hers, reconnecting their lips. Their heated makeout session continued as Kara ran her hands along Lena’s bare stomach, tingles shooting through Lena’s body as Kara caressed her skin. Lena’s own hands had finally left the back of the couch and began to unbutton Kara’s shirt painfully slow. But Lena wanted to take her time. To reveal her girlfriend’s beautiful body one button at a time. 

Lena had a bit of a thing for Kara’s muscles. Lena was by no means out of shape herself, but there was something about Kara’s feminine yet toned musculature that made her drool every time she saw her girlfriend in fewer clothes than normal. Once Lena had successfully undone all the buttons, she pushed the shirt off of Kara’s shoulders, who brought her back off the couch for a second, shrugging the shirt off. The two women were now making out heavily, shirtless on the couch, both borderline out of breath. 

Lena broke their kiss, sitting back for a second to admire her girlfriend’s upper body. “You are so beautiful, Kara,” Lena said reverently. Kara felt a surge of heat through her body as she watched Lena’s eyes sweep her body, those blueish green eyes dark with lust. Kara groaned, before reaching up to touch Lena’s breast through the woman’s black bra. Lena bit her lip at the sensation of Kara’s hand on her and her nipples hardened, straining against the bra. 

Kara grinned cheekily. “You look a little uncomfortable babe, let me help you with that.” With that, the blonde reached around and unclasped Lena’s bra, pulling it off the CEO and tossing it to the floor with their shirts. Lena now sat in Kara’s lap, completely topless with a horny Kryptonian staring at her like she was a goddess. Lena raised an eyebrow before leaning back down to capture Kara’s lips with her own. 

While Kara melted into the kiss, her hands began to massage Lena’s breasts, causing the raven haired woman to groan into the kiss. Lena’s own hand began to run itself down Kara’s abs, towards her center, softly touching Kara between her legs. Kara moaned, bucking her hips to meet Lena’s hand. Kara could feel wetness pooling in her underwear as Lena’s hand teased her through her pants. 

Kara detached her lips from Lena’s mouth and moved to kiss and suck (and occasionally bite) Lena’s neck, being sure to leave marks for later. Lena sighed happily at the sensations. She removed her hand from between Kara’s legs. The blonde whimpered at the loss of contact before Lena reached around Kara to undo her bra. Kara helped Lena remove the offending article of clothing and Lena tossed it over her head where it landed Rao knew where. 

The two women sat, now topless. Kara pulled Lena’s body closer to her, their breasts now pressed together. Kara stared into Lena’s eyes as the CEO bit her bottom lip. Kara gave Lena a lopsided smile before running a hand through Lena’s hair, pulling her head down into another searing kiss. Subtly, Lena’s hand made their way to Kara’s hands, flipping open the button and attempting to pull them down. Kara lifted herself slightly off the couch, allowing her pants to work their way down her thighs where she kicked them off, leaving the blonde in her, thoroughly soaked underwear. 

Lena’s lips migrated to one of Kara’s favorite spots behind her ear, kissing and nibbling on the patch of skin. Kara moaned softly as Lena’s hand made it’s way back between Kara’s legs. “Wow Kara, you are soaking.” Lena teased. Kara blinked before running her fingernails gently up and down Lena’s back. 

“All for you babe,” Kara replied. She heard a hitch in Lena’s breath. She felt Lena’s fingers start to tease her clit through the fabric. Kara closed her eyes as Lena went back to kissing behind Kara’s ear and sucking her earlobe. Kara’s own hands wandered her girlfriend’s body, running her fingers up and down Lena’s sides, causing the dark haired woman to shudder in pleasure. Lena knew that her underwear was probably just as wet as Kara’s. She needed to sink her fingers into Kara and she needed to do it soon. 

“I’m going to fuck you until you can’t walk Kara. Powers or no powers.” Lena whispered as she shoved her hand into Kara’s underwear, finally allowing her fingers to feel the wetness coming directly from Kara’s folds. The blonde loudly moans, letting out a string of incoherent words. Lena suspected they were probably in Kryptonian. She really had to get Kara to teach her the language at some point. 

Lena ran a finger up and down Kara’s slit, eliciting more groans from her girlfriend, the blonde’s hips bucking up to meet Lena’s finger desperately. Lena smirked at the effect she was having on the Kryptonian. She had to admit, it was kind of a power rush. Having someone as powerful as Supergirl writhing beneath her. It was exhilarating. “Fuck babe.” Kara gasped out as Lena’s fingers brushed Kara’s clit. 

“Tell me what you want Kara,” Lena said seductively. 

“I need… you.” Kara managed to gasp out as Lena just raised an eyebrow, looking her girlfriend in the eye. 

“Tell me exactly what you want Kara,” Lena repeated, wanting to hear the words directly out of Kara’s mouth. She knew the superhero had quite the foul mouth when she was this worked up. 

“I need you to fuck me, Lena. I want you to bury your fingers inside me.” Kara all but growled, gripping Lena’s hips tightly. It wasn’t enough to hurt Lena, no. Lena trusted Kara with her life. She knew that Kara could control herself. But Lena was going to have to wear something high waisted the next day to hide the hand marks. Though Lena smirked at Kara’s words. She leaned in, inches from Kara’s mouth. 

“Just remember, you asked for this darling.” Lena purred, kissing Kara sweetly on the nose before plunging two fingers into Kara’s center. The blonde shut her eyes tightly and screamed a little bit at the sudden intrusion. She bucked her hips, meeting Lena’s thrusts. The CEO started out painfully slow, pulling her fingers nearly out of Kara, before shoving them back in, rubbing Kara’s walls for a second when she had reached the superhero’s limit. 

One of Kara’s hands gripped the back of the couch tightly, slightly ripping the fabric, while her other hand was on Lena’s head, her fingers threaded through Lena’s thick, dark hair. Lena loved the rush that fucking Kara gave her. Another thing to love about the blonde. Lena worked her fingers in and out of Kara while the blonde began to pepper kisses along Lena’s neck and collarbone. Lena threw her head back, allowing Kara fuller access, resting the back of her head in Kara’s hand. 

Kara licked the expanse of Lena’s pale neck. Her own hips still bucking to meet Lena’s fingers. Lena could sense Kara’s breath quickening and feel her walls tightening around her fingers. She knew Kara was close. She could be evil and pull her fingers out. Bring Kara to the edge, only to leave her there for later. But Lena was too turned on herself to do that to Kara. Her girlfriend was also an extremely attentive lover and once she had finished with Kara, she was looking forward to what Kara was going to do to her. So she instead, she inserted a third finger into Kara. 

Kara gasped as being filled further but welcomed the feeling. “Rao Lena,” Kara mumbled against her lover’s neck. “Please.” She whined. Lena quickened the pace of her thrusts and started to stroke Kara’s clit with her thumb. Kara felt herself approach the edge and sucked harder on Lena’s neck, peppering it with marks that were probably going to bruise in the morning. It didn’t take long for Kara’s walls to fully tighten around Lena’s fingers, the blonde screaming out against Lena’s skin in ecstasy. 

The CEO grinned to herself, proud of the reaction her girlfriend had to her ministrations. She felt Kara tighten around her fingers so she slowed her thrusts, allowing Kara to ride out her orgasm. Her eyes drifting down to Kara to was still attached to her neck. But her body was shaking slightly as she milked Lena’s fingers for what seemed like hours. Kara’s breathing slowed and Lena pulled her fingers out of Kara and out of her underwear. She brought her fingers up to her mouth, licking them of Kara’s juices. Kara had long since detached herself from her lover’s neck and was now laying back, lazily against the couch. Her eyes darkened at the sight of Lena’s tongue lapping up the liquid that coated her fingers. 

“You taste exquisite darling,” Lena said seductively, a lustful glint in her eyes. Kara blinked before lunging forward, pushing Lena over to the side, reversing their positions so she was sitting on Lena’s lap. The CEO yelped but still held her lust filled gaze at her girlfriend who was now sitting in her lap. Kara’s index finger ran from Lena’s chin, down between her breasts, down her abs and to her pants. Kara tugged at the sweatpants that Lena was in, and pulled them down, along with her underwear so her girlfriend was naked on the couch under her. 

“Kara.” It was Lena’s turn to whimper. Kara smirked, her enhanced hearing picking up Lena’s increased heartbeat. She slowly reached down between Lena’s legs, running her finger down Lena’s slit once, bringing it back up. 

“Wow babe, you are soaking wet. Is this all for me?” Lena nodded furiously.

“It’s all for you darling.” The CEO agreed. Kara leaned in to kiss Lena’s lips, tasting herself on her girlfriend’s lips. Kara slowly kissed her way down Lena’s neck, pausing at her breasts to suck on Lena’s nipples for a minute before slowly climbing off of Lena, eventually kneeling on the floor in front of Lena, kissing her girlfriend’s stomach, peppering chaste kisses against Lena’s pale skin. 

“Kara, please,” Lena whispered. If it hadn’t been for her super hearing, she probably wouldn’t have heard her. Kara complied with a smirk, sitting back on her heels, starting at Lena. The CEO whimpered, biting her lip in anticipation. Kara had never seen a more beautiful sight had she had been to numerous different planets in her lifetime. 

Kara leaned in slowly, placing kisses on the insides of Lena’s thighs. Kara continued to place soft kisses around where Lena really wanted Kara’s mouth, teasing her girlfriend. Though she did take some pity and reached up to massage Lena’s breasts her one of her hands. She listened to Lena’s increase heartbeat and shallow breathing. The occasional “fuck” when Kara got close to Lena’s center. 

Eventually, Kara took pity of her girlfriend. Her juices were dripping out of her slit in anticipation. “Where do you want me, babe?” Kara asked seductively, looking up into Lena’s eyes. The woman just groaned. 

“I want your tongue inside me, Kara. Fuck. Please.” Lena nearly shouted. Kara chuckled, but complied, removing her hand from Lena’s breast, only to place one hand on each of Lena’s thighs, pushing her legs apart, diving in and trusting her tongue into Lena’s slit. The dark haired businesswoman moaned loudly, her hands flying to Kara’s head, her fingers running through her messy blonde hair. 

“Oh God. Kara. Fuck.” Lena groaned out as Kara lapped at Lena’s core. Lena threw her head back against the couch, letting out a string of expletives that her mother would have slapped her for saying in mixed company. Kara, for her part, loved the taste of Lena. Her reveled in eating her girlfriend out. Her nose brushed against Lena’s clit, eliciting a shudder from the woman on the couch. 

Kara withdrew her tongue from Lena’s core, the CEO whimpering at the loss of contact before moaning when Kara began to lick and suck on her clit. “Kara, please. Don’t stop.” Lena managed to gasp out. Kara had no intention of stopping anytime soon. She intended that it was going to be Lena that wouldn’t be able to walk to the bedroom later that evening. 

From Lena’s rapid heartbeat and shallow, quick breaths, she knew Lena was close. So the blonde removed one of her hands from Lena’s thigh, thrusting her index and middle finger into her girlfriend. Lena gasped, her hips gyrating against Kara’s tongue more fiercely. Kara bit Lena’s clit gently and that was enough for Lena’s walls to tighten against Kara’s fingers, juices gushing to coat Kara’s fingers as Lena rode out her own orgasm. The woman herself blacked out for a second or two as she came around Kara’s fingers. 

Kara continued to softly lick at Lena’s clit as she fell over the edge. When Kara was satisfied with herself, she looked up to see a content smile on Lena’s face, her head still laying on the back of the couch, looking up at the ceiling. Kara made her way off the floor, on top of Lena, resting her body against her girlfriend. Kara snuggled up to Lena’s neck, placing gentle kisses against the sweat soaked skin. Lena looked down at Kara, pulling her face up to kiss her girlfriend. She tasted herself on Kara’s tongue and sucked on Kara’s tongue, pulling her girlfriend closer. 

The two broke the kiss. Lena laid back, raising an eyebrow. “So, we can both still walk. Ready for round three?” She teased. Kara gave Lena an evil looking grin, a lustful glint still in her eyes. 

“Don’t start something you can’t finish babe.” Kara retorted. Lena blinked but beckoned Kara to come closer with her index finger. Lena then whispered into her ear. 

“Oh, I intend to finish it. And you. All evening.” 

**Author's Note:**

> Honestly, I don't even care about the prompt. I just wanted an excuse to write sin. It's my first formally published sin besides a collab smut scene I did with an anon in my inbox on Tumblr. I've never fancied myself a good smut writer, but I suppose I'll let the readers be the judge of that. Let me know. 
> 
> Also, I've always been annoyed as fuck that most stories (and honestly the show itself sometimes) make Kara either of average human intelligence or only slightly ahead in say science. Like she gets bored and doesn't understand things that Lena, Alex or Winn are talking about. She's an alien from a very advanced scientific culture, daughter of the Head of the Science Guild who reads information crystals in her spare time before she left Krypton. She's not an idiot. 
> 
> It's also probably riddled with mistakes because I didn't go back and proof read it. I might later. When I'm in the mood.
> 
> Feel free to come scream at me or with me on Tumblr: aeon-wolf.tumblr.com


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